A few cattle are found dead in pastures every year, their demise due to eating poisonous plants.
Good management could have prevented many of these deaths.
“This year, there is particular need for producers to be aware of any poisonous plants in their pastures,” says Todd Jorgenson, a rangeland agrologist with Saskatchewan Agriculture.
He said poisonous plants are found across the Prairies, but animals seldom eat them if good forage is available.
“Overgrazing or drought, however, often forces stock to eat plants not typically grazed.”
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Overgrazing also reduces the number and size of good forage species, and increases less palatable plants.
When native pastures are grazed before they are ready, the earliest species are forced to carry the grazing load.
“Some early growing plants are quite poisonous and are often the species that cause livestock losses,” Jorgenson said.
Poisonous plants common to hillsides include death camas, a slender perennial herb with V-shaped grass-like leaves.
It grows 20 to 40 centimetres tall, has many creamy-yellow flowers, and grows from a bulb that resembles an onion.
It is often confused with wild onion, which has pink flowers and an onion odor.
Poisonous plants common to hillsides and open pasture include early yellow locoweed and narrow-leaved milk-vetch.
Locoweed is a low-growing member of the pea family. It has a deep taproot, yellowish flowers and leaves that have seven to 21 leaflets.
Narrow-leaved milk-vetch is a semi-erect, branched herb that grows one-third to two-thirds of a metre tall with noticeable cream-colored flowers.
Milk vetches usually indicate high levels of selenium in the soil. High levels of this inorganic element accumulate in milk-vetch, especially after drought. Selenium is poisonous, even in cut hay.
Alkaline sloughs are home to arrow-grass, a rush-like herb that grows 15 to 75 cm high.
The newer leaves are smooth, shiny, bright green, clumped and unbranched. The flower stalks are taller, with small, clustered, greenish flowers.
The young new leaves are more poisonous than older parts of the plant.
Western water hemlock, which is the deadliest plant in most prairie regions, grows in marshy sloughs, wet meadows and stream banks. It grows .6 to 1.8 m tall, and has large, alternate leaves with saw-toothed edges.
The tuberous root contains a poisonous yellow oil. One root can kill a mature cow.
“Poisoned animals are usually difficult to treat, as there is often no known antidote, or none that can be given under range conditions. Usually the first evidence of poisoning is discovery of the dead animal, often in remote areas.”
The best way to prevent losses is to know the common poisonous plants and, through management, maintain an abundance of desired, palatable forage.
A veterinarian should be consulted when stock die to determine the cause of death, which prevents further losses.
Samples of plants suspected of being poisonous should be taken to the local agrologist for identification, Jorgenson said.
Illustrated field guides are available at Saskatchewan rural service centres: Identification of Common Range Plants of Northern Sask-atchewan; Identification of Common Range Plants of Southern Saskatchewan; and Identification of Common Riparian Plants of Saskatchewan.
